Apparatus for endoscopic procedures

ABSTRACT

A surgical stapling apparatus includes a handle assembly, a shaft assembly extending distally from the handle assembly, and an end effector selectively detachable from the shaft assembly. The end effector includes a first jaw member and a second jaw member. The first jaw member supports a lever that is pivotally movable relative to the first jaw member between an extended position and a retracted position. The lever is in contact with a leaf spring to spring bias the lever to the extended position. The second jaw member supports a drive beam that is selectively engagable with the lever to facilitate a pivotal movement of the second jaw member relative to the first jaw member between an unapproximated state and an approximated state.

TECHNICAL FIELD

The present disclosure relates to surgical apparatus, devices and/or systems for performing endoscopic surgical procedures and methods of use thereof. More specifically, the present disclosure relates to electromechanical, hand-held surgical apparatus, devices and/or systems configured for use with removable disposable loading units and/or single use loading units for clamping, cutting, and/or stapling tissue.

BACKGROUND

A number of surgical device manufacturers have developed product lines with proprietary drive systems for operating and/or manipulating electromechanical surgical devices. Some electromechanical surgical devices include a handle assembly, which is reusable, and replaceable loading units and/or single use loading units or the like that are selectively connected to the handle assembly prior to use and then disconnected from the handle assembly following use, in order to be disposed of or in some instances sterilized for re-use.

Many of these electromechanical surgical devices are relatively expensive to manufacture, purchase, and/or operate. There is a desire by manufactures and end users to develop electromechanical surgical devices that are relatively inexpensive to manufacture, purchase, and/or operate.

Accordingly, a need exists for electromechanical surgical apparatus, devices and/or systems that are relatively economical to develop and manufacture, to store and ship, as well as economical and convenient to purchase and use from the end user's perspective.

SUMMARY

According to one aspect of the present disclosure, an end effector includes a mounting portion and first and second jaw members that extend distally from the mounting portion. A fastener cartridge is secured to the second jaw member. The fastener cartridge supports a plurality of fasteners in fastener retaining slots defined in a tissue engaging surface of the fastener cartridge.

In another aspect, a surgical stapling apparatus includes a handle assembly, a shaft assembly extending distally from the handle assembly, and an end effector selectively detachable from the shaft assembly. In embodiments the surgical stapling apparatus is powered.

The first jaw member includes a tissue engaging surface and may support a lever assembly. The second jaw member may support a drive beam that is selectively engagable with the lever assembly to facilitate a pivotal movement of the second jaw member relative to the first jaw member between an unapproximated state and an approximated state. The first jaw member may define a ramp. The drive beam may be engagable with the ramp to pivot the first jaw member and the second jaw member to the approximated state and enable the drive beam to distally translate along the first and second jaw members.

The drive beam may configured to disengage from the lever assembly, to distally translate along the first jaw member and the second jaw member to approximate the first and second jaw members relative to one another, and distally translate along the fastener cartridge to fire the plurality of fasteners from the fastener retaining slots and form the plurality of fasteners against the tissue engaging surface of the first jaw member. The drive beam may define a notch therein and may support a knife adapted to cut tissue as the drive beam translates along the fastener cartridge.

The lever assembly may include a lever pivotally connected to the first jaw member and pivotally movable relative to the first jaw member between an extended position and a retracted position. The lever may be engaged with the notch of the drive beam when the first and second jaw members are in the unapproximated state, when the drive beam is in a proximal position, and when the lever is in the extended position. The lever may be engaged with the notch of the drive beam to limit distal translation of the drive beam prior to the second jaw member pivoting relative to the first jaw member from the unapproximated state to the approximated state. The lever may be configured to disengage from the notch as the lever pivots from the extended position to the refracted position in response to the second jaw member pivoting relative to the first jaw member from the unapproximated state to the approximated state. The drive beam may be distally translatable when the first and second jaw members are in the approximated state and the lever is in the retracted position.

A spring assembly may be supported by the first jaw member. The spring assembly may include a spring configured to contact the lever to bias the lever to the extended position. The spring may be a leaf spring.

A drive screw may be supported by the second jaw member that is operably associated with the drive beam to translate the drive beam as the drive screw rotates. The drive beam may include a retention foot that threadably receives the drive screw. The drive screw may be coupled to a rotatable drive member, wherein rotation of the drive screw in the retention foot facilitates pivotal movement of the second jaw member relative to the first jaw member and translation of the drive beam through the fastener cartridge. The drive screw may have a head projecting from a proximal end portion thereof. The head may define a pivot axis therethrough that is transverse to a longitudinal axis of the end effector between proximal and distal end portions of the end effector. The second jaw member may be configured to pivot relative to the first jaw member about the pivot axis.

Other aspects, features, and advantages will be apparent from the description, the drawings, and the claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above, and the detailed description of the embodiment(s) given below, serve to explain the principles of the disclosure, wherein:

FIG. 1 is a perspective view of an electromechanical surgical system according to the principles of the present disclosure;

FIG. 2 is a perspective view, with parts separated, of the electromechanical surgical system of FIG. 1;

FIG. 3 is a front, perspective view of an end effector of the electromechanical surgical system of FIGS. 1 and 2;

FIG. 4 is a rear, perspective view of the end effector of FIG. 3;

FIG. 5 is a perspective view, with parts separated, of the end effector of FIGS. 3 and 4;

FIG. 6 is a side, cross-sectional, perspective view of the end effector of FIGS. 3-5, as taken through 6-6 of FIG. 4, showing the end effector in an unapproximated state;

FIG. 7 is an enlarged view of the indicated area of detail shown in FIG. 6;

FIG. 8 is a side, cross-sectional view of the end effector showing a drive beam thereof in a partially advanced position;

FIG. 9 is an enlarged view of the indicated area of detail shown in FIG. 8;

FIG. 10 is a side, cross-sectional view of the end effector in an approximated state with the drive beam thereof shown in a partially advanced position;

FIG. 11 is an enlarged view of the indicated area of detail shown in FIG. 10;

FIG. 12 is an enlarged, partial, cross-sectional view of the end effector showing the drive beam partially advanced; and

FIG. 13 a side, cross-sectional view of the end effector in an approximated state with the drive beam thereof shown in a distally advanced position.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the presently disclosed electromechanical surgical system, apparatus and/or device are described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein the term “distal” refers to that portion of the electromechanical surgical system, apparatus and/or device, or component thereof, that are farther from the user, while the term “proximal” refers to that portion of the electromechanical surgical system, apparatus and/or device, or component thereof, that are closer to the user.

Referring initially to FIGS. 1 and 2, an electromechanical, hand-held, powered surgical system is shown and generally designated 10. Electromechanical surgical system 10 includes a surgical apparatus or device in the form of an electromechanical, hand-held, powered surgical instrument 100 that is configured for selective attachment thereto of a plurality of different end effectors 400, via a shaft assembly 200, that are each configured for actuation and manipulation by the electromechanical, hand-held, powered surgical instrument 100. In particular, surgical instrument 100 is configured for selective connection with an articulation assembly 300 of shaft assembly 200, and, in turn, shaft assembly 200 is configured for selective connection with any one of a plurality of different end effectors 400 via articulation assembly 300.

Reference may be made to U.S. Patent Application Publication No. 2009/0101692, U.S. Patent Application Publication No. 2011/0121049, and U.S. Patent Application Publication No. 2013/0098966, the entire content of each of which is hereby incorporated herein by reference, for a detailed description of the construction and operation of exemplary electromechanical, hand-held, powered surgical instruments, the components of which are combinable and/or interchangeable with one or more components of powered surgical system 10 described herein.

Generally, as illustrated in FIGS. 1 and 2, surgical instrument 100 includes an instrument housing 102 having a lower housing portion 104, an intermediate housing portion 106 extending from and/or supported on lower housing portion 104, and an upper housing portion 108 extending from and/or supported on intermediate housing portion 106. The surgical instrument 100 has a controller (not shown) for controlling certain functions of the surgical system, collecting data, and performing other functions. Instrument housing 102 defines a cavity (not shown) therein in which a circuit board (not shown) and a drive mechanism (not shown) are situated.

The circuit board is configured to control the various operations of surgical instrument 100, as will be set forth in additional detail below. In accordance with the present disclosure, instrument housing 102 provides a housing in which a rechargeable battery (not shown), is removably situated. The battery is configured to supply power to any of the electrical components of surgical instrument 100.

Upper housing portion 108 of instrument housing 102 has a nose or connecting portion 108 a configured to accept a corresponding shaft coupling assembly 204 of transmission housing 202 of shaft assembly 200. As seen in FIG. 2, connecting portion 108 a of upper housing portion 108 of surgical instrument 100 defines a cylindrical recess 108 b that receives shaft coupling assembly 204 of transmission housing 202 of shaft assembly 200 when shaft assembly 200 is mated to surgical instrument 100. The connecting portion 108 a of the surgical instrument 100 has at least one rotatable drive member. In some embodiments, connecting portion 108 a houses a plurality of rotatable drive members or connectors (not shown), each drive member of the plurality of drive members can be independently, and/or dependently, actuatable and rotatable by the drive mechanism (not shown) housed within instrument housing 102.

Upper housing portion 108 of instrument housing 102 provides a housing in which the drive mechanism (not shown) is situated. The drive mechanism is configured to drive shafts and/or gear components in order to perform the various operations of surgical instrument 100. In particular, the drive mechanism is configured to drive shafts and/or gear components in order to selectively move end effector 400 relative to shaft assembly 200; to rotate anvil assembly 200 and/or end effector 400, about a longitudinal axis “X1” (see FIGS. 1 and 2), relative to instrument housing 102; to move an upper jaw member or anvil assembly 410 of end effector 400 relative to a lower jaw member or cartridge assembly 420 of end effector 400; to articulate and/or rotate the shaft assembly 200; and/or to fire a fastener cartridge 420 a within cartridge assembly 420 of end effector 400.

In accordance with the present disclosure, the drive mechanism may include a selector gearbox assembly (not shown); a function selection module (not shown), located proximal to the selector gearbox assembly, that functions to selectively move gear elements within the selector gearbox assembly into engagement with a second motor (not shown). The drive mechanism may be configured to selectively drive one of drive members or connectors of surgical instrument 100, at a given time.

As illustrated in FIGS. 1 and 2, instrument housing 102 supports a pair of finger-actuated control buttons 124, 126 and/or rocker device(s) 130 (only one rocker device being shown). Each one of the control buttons 124, 126 and rocker device(s) 130 includes a respective magnet (not shown) that is moved by the actuation of an operator. In addition, the circuit board (not shown) housed in instrument housing 102 includes, for each one of the control buttons 124, 126 and rocker device(s) 130, respective Hall-effect switches (not shown) that are actuated by the movement of the magnets in the control buttons 124, 126 and rocker device(s) 130. The actuation of Hall-effect switch (not shown), corresponding to control buttons 124, 126 causes the circuit board to provide appropriate signals to the function selection module and the input drive component of the drive mechanism to open/close end effector 400 and/or to fire a stapling/cutting cartridge within end effector 400.

Similarly, the actuation of the Hall-effect switch, corresponding to rocker device 130, causes the circuit board to provide appropriate signals to the function selection module and the input drive component of the drive mechanism to rotate end effector 400 relative to shaft assembly 200 or rotate end effector 400 and shaft assembly 200 relative to instrument housing 102 of surgical instrument 100. Specifically, movement of rocker device 130 in a first direction causes end effector 400 and/or shaft assembly 200 to rotate relative to instrument housing 102 in a first direction, while movement of rocker device 130 in an opposite, e.g., second, direction causes end effector 400 and/or shaft assembly 200 to rotate relative to instrument housing 102 in an opposite, e.g., second, direction.

Turning now to FIGS. 3-13, end effector 400 is shown and described. End effector 400 is configured and adapted to apply a plurality of linear rows of fasteners “F” (e.g., staples, see FIG. 5). In certain embodiments, the fasteners are of various sizes, and, in certain embodiments, the fasteners have various lengths or rows, e.g., about 30, 45 and 60 mm in length.

As seen in FIGS. 3 and 4, end effector 400 includes a mounting portion 430 coupled to a jaw assembly 415. A proximal end portion of mounting portion 430 is configured for selective connection to a distal end portion of shaft assembly 200 (e.g., articulation assembly 300) that has complementary structure formed thereon. Jaw assembly 415 is connected to, and extends distally from, mounting portion 430. Jaw assembly 415, as will be discussed in greater detail below, includes lower jaw member 420, which is configured to selectively support fastener cartridge 420 a therein, and upper jaw member 410, each of which is secured to mounting portion 430 to enable relative movement between upper and lower jaw members 410, 420. Jaw assembly 415 is pivotally movable to orient upper and lower jaw members 410, 420 between approximated and unapproximated states.

With reference to FIG. 5, upper jaw member 410 includes an anvil body 410 a with a fastener forming surface 411 including a plurality of staple forming pockets (not shown), arranged in longitudinally extending rows and configured to form the fasteners upon a firing of end effector 400, as appreciated by one skilled in the art. Anvil body 410 a supports a leaf spring assembly 412 and a lever assembly 414 that are supported within a chamber 410 b of body 410 a. Leaf spring assembly 412 and lever assembly 414 are enclosed within chamber 410 b by a cover 410 c that is selectively removable from body 410 a. Together, leaf spring assembly 412 and lever assembly 414 function to bias jaw assembly 415 in the unapproximated state and enable pivotal movement of the jaw assembly 415 between the approximated and unapproximated states as described in greater detail herein.

Leaf spring assembly 412 includes a leaf spring 412 a that is mounted to body 410 a at a first end of leaf spring 412 a by a mounting plate 412 b and a fastener 412 c. Leaf spring 412 a extends to an engagement tip 412 d at a second end of leaf spring 412 a that can have any suitable configuration such as a curvilinear scoop.

Lever assembly 414 includes a lever 414 a that defines a pin channel 414 c on one end thereof and a distal tip 414 b on an opposite end thereof. Lever 414 is pivotally mounted to anvil body 410 a by a pin 414 d that is received through pin channel 414 c of lever 414 a and a pin channel 410 d defined in anvil body 410 a.

Anvil body 410 a defines a plurality of bores on a proximal end of anvil body 410 a including a drive bore 410 e that receives a drive assembly 416, a pair of plunger bores 410 f that receives a pair of plunger assemblies 418, and a electrical contact bore 410 g that receives an electrical contact member 417 that functions to electrically communicate with instrument housing 102 when end effector 400 is secured to shaft assembly 200. Drive assembly 416 includes a drive member 416 a, a gear member 416 b coupled to drive member 416 a, and a mounting plate 416 c that supports drive member 416 a and gear member 416 b. Each plunger assembly of the pair of plunger assemblies 418 includes a plunger 418 a that receives a spring 418 b that functions to spring bias plunger 418 a in a distal direction to facilitate securement of fastener cartridge 420 a to cartridge assembly 420. Plunger 418 a defines a pin slot 418 c that receives a pin 418 d to secure each plunger assembly within a respective one of the pair of plunger bores 410 f when pin 418 d is received within a pin channel 410 h defined within anvil body 410 a.

Lower jaw member 420 is configured and adapted to selectively receive fastener cartridge 420 a. Fastener cartridge 420 a includes a tissue engaging surface 423 a that defines a plurality of rows of fastener retaining slots 423 b adapted to support the plurality of fasteners “F” (and a plurality of staple pushers, not shown, but can be appreciated by those skilled in art). Fastener cartridge 420 a also includes a longitudinally extending knife slot 423 c disposed between pairs of rows of fastener retaining slots 423 b that is adapted to enable drive beam 426 to axially translate therethrough.

Lower jaw member 420 includes a mounting member 420 b, in the form of a channel, that supports fastener cartridge 420 a and a base member 420 c couplable to mounting member 420 b. Mounting member 420 b includes a mounting body 421 having a pair of wings 421 a that extends proximally therefrom. The pair of wings 421 a define a fastener channel 421 b therethrough that is dimensioned to receive fasteners 440 advanced into a pair of passages 410 i defined in upper jaw member 410 for securing upper jaw member 410 to lower jaw member 420. A slot 421 c and a screw passage 421 d are defined in a plate 421 e of mounting body 421 positioned adjacent to the pair of wings 421 a.

An actuation sled 422 is supported by lower jaw member 420 and is adapted to advance through fastener cartridge 420 a to fire the plurality of fasteners supported with fastener cartridge 420 a as one skilled in the art will appreciate. Lower jaw member 420 rotatably supports a drive screw 424 therein that extends substantially an entire length of lower jaw member 420. Drive screw 424 is threadably engaged with drive beam 426, which is axially slidably supported in lower jaw member 420 between proximal and distal positions in response to rotation of drive screw 424, as described in greater detail below. Drive screw 424 includes a multi-faceted head 424 a, a pair of retention members 424 b that define an annular channel 424 c therebetween, and a distally extending threaded shaft 424 d. Drive screw 424 extends through screw passage 421 d so that a bracket 428, which defines a U-shaped channel 428 a therethrough, secures drive screw 424 to mounting member 420 b when bracket 428 is received in slot 421 c and positioned within annular channel 424 c. Bracket 428 and mounting member 420 b cooperate to axially and lateral fix drive screw 424 in lower jaw member 420 while enabling drive screw 424 to rotate.

Drive beam 426 has a substantially I-shaped cross-sectional profile configured to progressively approximate lower jaw member 420 and upper jaw member 410 as drive beam 426 travels through knife slot 423 c in fastener cartridge 420 a. Drive beam 426 functions to axially displace actuation sled 422 through lower jaw member 420 and includes a retention foot 426 a having an internally threaded bore 426 f, a vertically oriented support strut 426 b supported on retention foot 426 a, and a lateral projecting member 426 c formed atop support strut 426 b. Lateral projecting member 426 c defines a notch 426 d formed in an upper surface thereof. Vertically oriented support strut 426 b supports a knife 426 e thereon that is adapted to cut tissue.

FIG. 5 illustrates that mounting portion 430 is secured to the proximal end portion of upper jaw member 410. Mounting portion 430 includes a first member 432, a second member 434, and a third member 436 that are coupled together and support a spring assembly 438. Spring assembly 438 includes a plunger 438 a and a spring 438 b.

Referring now to FIGS. 6 and 7, end effector 400 is shown in an initial and/or unapproximated state, in which upper jaw member 410 is spaced from lower jaw member 420 relative to a longitudinal axis “X2” defined through end effector 400. In the unapproximated state, lower jaw member 420 is positioned at an acute angle (e.g., 15 degrees) relative to upper jaw member 410, drive screw 424 is disposed at an acute angle relative to mounting portion 430, and head 424 a of drive screw 424 is supported at an acute angle within a bore 416 d defined by drive member 416 a.

As depicted in FIG. 7, when end effector 400 is in the unapproximated state, lever 414 a is disposed in an extended position, due to spring biasing forces applied to lever 414 a by leaf spring assembly 412, through contact with engagement tip 412 d of leaf spring 412 a. Drive beam 426 is disposed in a proximal-most position and leaf spring 412 a of leaf spring assembly 412 is disposed in an unflexed state. In the extended position of lever 414 a, distal tip 414 b of lever 414 a is disposed in notch 426 d of lateral projecting member 426 c of drive beam 426.

With reference to FIGS. 8 and 9, rotation of drive member 416 a rotates head 424 a of drive screw 424, which imparts rotation to drive screw 424. The pair of retention members 424 b maintain drive screw 424 longitudinally fixed as the drive member 416 a imparts rotational movement to drive screw 424. With drive screw 424 being threadably engaged with retention foot 426 a of drive beam 426, rotational movement of drive screw 424 distally translates drive beam 426, as indicated by arrow “A.” In this regard, distal tip 414 b of lever 414 a engages a notch sidewall 426 g of drive beam 426, preventing distal translation of drive beam 426 and causing lower jaw member 420 to pivot relative to upper jaw member 410 in the direction indicated by arrow “B” and about a pivot axis “P” that is defined transversely through head 424 a of drive screw 424. As lower jaw member 420 pivots toward upper jaw member 410, closing and/or approximating upper and lower jaw members 410, 420, drive beam 426 engages a bottom surface of lever 414 a so that lever 414 a pivots, counterclockwise (as illustrated in FIG. 9, albeit clockwise when viewed from the opposite side of end effector 400), toward upper jaw member 410 in the direction indicated by arrow “B” against spring biasing forces applied to a top surface of lever 414 a through engagement tip 412 d of leaf spring assembly 412. In response to pivoting movement of lever 414 a toward upper jaw member 410, leaf spring 412 a begins to flex to a flexed state in the direction indicated by arrow “B” so that leaf spring 412 a pivots, clockwise (as illustrated in FIG. 9, albeit counterclockwise when viewed from the opposite side of end effector 400), relative to fastener 412 c, toward upper jaw member 410.

As seen in FIGS. 10 and 11, further rotational movement of drive screw 424 pivots lever 414 a so that distal tip 414 b of lever 414 a separates from notch 426 a enabling lever 414 a to pivot toward a retracted position and enabling lower jaw member 420 to continue to pivot toward upper jaw member 410, as indicated by arrow “C,” until upper and lower jaw members 410, 420 are positioned in the approximated state. Upon separation of distal tip 414 b of lever 414 a and notch 426 a of drive beam 426, continued rotational movement of drive screw 424 distally translates drive beam 426, as indicated by the arrow “A,” beneath lever 414 a along the bottom surface of lever 414 a or lever assembly 414. Distal translation of drive beam 426 drives lever 414 a to the retracted position in which distal tip 414 b engages a bottom surface of leaf spring 412 a at a point 412 e along leaf spring 412 a, separating engagement tip 412 d from a top surface of lever 414 a.

With reference to FIGS. 12 and 13, when upper and lower jaw members 410, 420 are in the approximated state, lower jaw member 420 is positioned in parallel with upper jaw member 410, and head 424 a of drive screw 424 is supported within a bore 416 d of drive member 416 a so that drive screw 424 is parallel to upper jaw member 410. In the approximated state, continued rotation of drive screw 424 distally translates drive beam 426 through end effector 400 toward a distal end portion of end effector 400, as indicated by arrow “A.” Upon translating drive beam 426, distally past lever assembly 414, leaf spring assembly 412 urges lever assembly 414 to the extended position. Continued rotation of drive screw 424 advances actuation sled 422 through fastener cartridge 420 a to fire the plurality of fasteners stored within fastener cartridge 420 a for securing to tissue.

Drive screw 424 can then be rotated in an opposite direction to retract drive beam 426 proximally to the proximal-most position. More particularly, drive beam 426 is retracted proximally until drive beam 426 engages lever assembly 414, which under the spring bias of leaf spring assembly 412, urges upper and lower jaw members 410, 420 apart so that upper and lower jaw members 410, 420 are disposed in the original or unapproximated state as shown in FIG. 6. Fastener cartridge 420 a can then be removed, disposed of, and/or replaced, as desired, and the operation of end effector 400 described above can be repeated as necessary with a new, un-fired fastener cartridge 420 a loaded in lower jaw member 420.

In embodiments, end effector 400 supports one or more computer or microchips (not shown) that electrically communicate signals or identification codes to the controller and/or circuit board of surgical instrument 100. The signals or identification codes can indicate whether or not fastener cartridge 420 a, or portions thereof, is at least partially fired, unfired, etc. the chip may store certain specifications such as the cartridge size, staple arrangement, stale length, clamp-up distance. The chip may store a code that indicates that the end effector has been used to prevent reuse of an empty or previously used end effector. The chip may store a unique identification code for the end effector. The information on the chip may be encrypted to prevent tampering. Reference may be made to U.S. patent application Ser. No. 13/968,563, filed on Aug. 16, 2013 (H-US-03833), the entire contents of which is incorporated herein by reference, for a detailed discussion of an exemplary end effector supporting one of more computer or microchips.

Persons skilled in the art will understand that the structures and methods specifically described herein and shown in the accompanying figures are non-limiting exemplary embodiments, and that the description, disclosure, and figures should be construed merely as exemplary of particular embodiments. It is to be understood, therefore, that the present disclosure is not limited to the precise embodiments described, and that various other changes and modifications may be effected by one skilled in the art without departing from the scope or spirit of the disclosure. Additionally, the elements and features shown or described in connection with certain embodiments may be combined with the elements and features of certain other embodiments without departing from the scope of the present disclosure, and that such modifications and variations are also included within the scope of the present disclosure. Accordingly, the subject matter of the present disclosure is not limited by what has been particularly shown and described. 

The invention claimed is:
 1. An end effector, comprising: a mounting portion; a first jaw member extending distally from the mounting portion, the first jaw member including a tissue engaging surface and supporting a lever assembly, the lever assembly including a lever pivotally connected to the first jaw member and pivotally movable relative to the first jaw member between an extended position and a retracted position; a second jaw member extending distally from the mounting portion and supporting a drive beam, the drive beam being selectively engagable with the lever assembly to facilitate a pivotal movement of the second jaw member relative to the first jaw member between an unapproximated state and an approximated state; and a fastener cartridge secured to the second jaw member and supporting a plurality of fasteners in fastener retaining slots defined in a tissue engaging surface of the fastener cartridge, the drive beam being configured to disengage from the lever assembly, to distally translate along the first jaw member and the second jaw member to approximate the first and second jaw members relative to one another, and distally translate along the fastener cartridge to fire the plurality of fasteners from the fastener retaining slots and form the plurality of fasteners against the tissue engaging surface of the first jaw member.
 2. The end effector of claim 1, wherein the drive beam defines a notch therein, the lever being engaged with the notch when the first and second jaw members are in the unapproximated state, when the drive beam is in a proximal position, and when the lever is in the extended position, wherein the lever is engaged with the notch of the drive beam to limit distal translation of the drive beam prior to the second jaw member pivoting relative to the first jaw member from the unapproximated state to the approximated state.
 3. The end effector of claim 2, wherein the lever is configured to disengage from the notch as the lever pivots from the extended position to the retracted position in response to the second jaw member pivoting relative to the first jaw member from the unapproximated state to the approximated state.
 4. The end effector of claim 3, wherein the drive beam is distally translatable when the first and second jaw members are in the approximated state and the lever is in the retracted position.
 5. The end effector of claim 1, wherein the first jaw member supports a spring assembly, the spring assembly including a spring configured to contact the lever to bias the lever to the extended position.
 6. The end effector of claim 1, wherein the second jaw member supports a drive screw operably associated with the drive beam to translate the drive beam as the drive screw rotates.
 7. The end effector of claim 6, wherein the drive beam includes a retention foot that threadably receives the drive screw, the drive screw being coupled to a rotatable drive member, wherein rotation of the drive screw in the retention foot facilitates pivotal movement of the second jaw member relative to the first jaw member and translation of the drive beam through the fastener cartridge.
 8. The end effector of claim 6, wherein the drive screw has a head projecting from a proximal end portion thereof, the head defining a pivot axis therethrough, the pivot axis being transverse to a longitudinal axis of the end effector between proximal and distal end portions of the end effector, the second jaw member configured to pivot relative to the first jaw member about the pivot axis.
 9. The end effector of claim 1, wherein the first jaw member defines a ramp, the drive beam being engagable with the ramp to pivot the first jaw member and the second jaw member to the approximated state and enable the drive beam to distally translate along the first and second jaw members.
 10. The end effector of claim 1, wherein the drive beam supports a knife adapted to cut tissue as the drive beam translates along the fastener cartridge.
 11. A powered surgical stapling apparatus, comprising: a handle assembly; a shaft assembly extending distally from the handle assembly; an end effector selectively detachable from the shaft assembly, the end effector including: a first jaw member including a tissue engaging surface and supporting a lever, the lever pivotally connected to the first jaw member and pivotally movable relative to the first jaw member between an extended position and a retracted position; a second jaw member supporting a drive beam, the drive beam being selectively engagable with the lever to facilitate a pivotal movement of the second jaw member relative to the first jaw member between an unapproximated state and an approximated state; and a fastener cartridge secured to the second jaw member and supporting a plurality of fasteners in fastener retaining slots defined in a tissue engaging surface of the fastener cartridge, the drive beam being configured to disengage from the lever, to distally translate along the first jaw member and the second jaw member to approximate the first and second jaw members relative to one another, and distally translate along the fastener cartridge to fire the plurality of fasteners from the fastener retaining slots and form the plurality of fasteners against the tissue engaging surface of the first jaw member.
 12. The powered surgical stapling apparatus of claim 11, wherein the drive beam defines a notch therein, the lever being engaged with the notch when the first and second jaw members are in the unapproximated state, when the drive beam is in a proximal position, and when the lever is in the extended position, wherein the lever is engaged with the notch of the drive beam to limit distal translation of the drive beam prior to the second jaw member pivoting relative to the first jaw member from the unapproximated state to the approximated state.
 13. The powered surgical stapling apparatus of claim 12, wherein the lever is configured to disengage from the notch as the lever pivots from the extended position to the retracted position in response to the second jaw member pivoting relative to the first jaw member from the unapproximated state to the approximated state.
 14. The powered surgical stapling apparatus of claim 13, wherein the drive beam is distally translatable when the first and second jaw members are in the approximated state and the lever is in the retracted position.
 15. The powered surgical stapling apparatus of claim 11, wherein first jaw member supports a leaf spring configured to contact the lever to bias the lever to the extended position.
 16. The powered surgical stapling apparatus claim 11, wherein the second jaw member supports a drive screw operably associated with the drive beam to translate the drive beam as the drive screw rotates.
 17. The powered surgical stapling apparatus of claim 16, wherein the drive beam includes a retention foot that threadably receives the drive screw, the drive screw being coupled to a rotatable drive member, wherein rotation of the drive screw in the retention foot facilitates pivotal movement of the second jaw member relative to the first jaw member and translation of the drive beam through the fastener cartridge.
 18. A surgical stapling apparatus, comprising: a handle assembly; a shaft assembly extending distally from the handle assembly; an end effector selectively detachable from the shaft assembly, the end effector including: a first jaw member supporting a lever that is pivotally connected to the first jaw member and pivotally movable relative to the first jaw member between an extended position and a retracted position, the lever being in contact with a leaf spring to spring bias the lever to the extended position; and a second jaw member supporting a drive beam, the drive beam being selectively engagable with the lever to facilitate a pivotal movement of the second jaw member relative to the first jaw member between an unapproximated state and an approximated state. 